Drugs and other liquids are customarily delivered to patients via their vascular systems, using a needle or catheter inserted into a peripheral blood vessel. Such techniques are generally satisfactory when the patient's blood pressure is at normal levels, and blood vessels can be readily located. However, in cases where the patient is in circulatory shock as a result of, for example, heart failure, drug overdose, or severe hemorrhaging, the peripheral blood vessels are frequently collapsed and access to the blood vessels is difficult. Furthermore, blood vessels may be difficult to locate under stress or other adverse conditions. Substantial delays in administering the drugs and liquids can therefore result and, in many instances, vascular access cannot be obtained at all. Severe injury to the patient or even death can result.
A suitable alternative to vascular infusion that is particularly useful when peripheral blood vessels are collapsed is intraosseous infusion. This technique first saw significant use during World War II, when sternal puncture kits for bone marrow infusions were included in emergency medical supplies, but has only recently been given significant attention in the medical literature. In intraosseous infusion, a resuscitative fluid or drug solution is injected directly into the bone marrow of the patient's bone, from where it is transported throughout the patient's body. Intraosseous infusion requires penetration of the patient's skin and outer bone by a needle or the like to gain access to the intraosseous space.
The intraosseous space within bone is often referred to as a non-collapsible vein. Bone consists of an outer layer of cortical bone and an inner medullary marrow cavity containing cancellous (i.e. spongy) bone tissue. The inner cavity is also referred to as the intraosseous space. The intraosseous space contains thousands of tiny non-collapsible blood vessels, and will transport substances quickly, generally within seconds, to the central veins in the body. Infants and children have only red marrow in the intraosseous space, which is gradually replaced with yellow marrow in the bones of adults. Blood flow through the intraosseous space is relatively constant, even in most cases of shock, and blood pressure is typically about 35/25 mmHg, which is about a third of systemic arterial blood pressure.
Among the earliest devices for intraosseous (IO) infusion were manually inserted IO devices. These devices included modified steel needles with removable trocars to prevent plugging with bone fragments and special handles to allow the operator to push into the bone while rotating. These devices were used primarily in pediatrics because children's bones are softer than adults and children's blood vessels are often particularly difficult to locate. More recently, IO infusion devices have been developed for IO infusion for adults. These include the First Access for Shock and Trauma (FAST), described in U.S. Pat. No. 5,817,052, and the Bone Injection Gun (BIG), described in U.S. Pat. No. 5,591,188. These are both impact-driven devices in which a powerful spring drives a needle into the bone to a certain depth. More recently, a battery-powered IO access device using a specially designed drill-tipped need has been developed, in which a battery-powered motor drives the needle into the bone, as described in U.S. patent application Ser. No. 10/449,476, entitled “Apparatus and Method to Access Bone Marrow.” However, these devices all require the bone to be penetrated at the time IO infusion is needed, and can be stymied by various problems such as bent needles, operator inexperience, or even failed power supplies.